1. Field of the Invention
This invention pertains generally to optical transceivers and, in particular, to an optical device package for an optical transceiver.
2. Discussion of the Background
Optical transceivers are known in the art and include active optical devices or diode packages. Common diode packages include LED packages such as a TO-46 package or a 5.6 mm TO style laser diode package such as RLD-85PC diode package by Rohm, Incorporated. These diode packages or TO cans typically include a metallic housing having a laser diode or LED for transmitting data and a photo diode for performing power-monitoring, metal contact leads exiting from the diodes for connection to a power source and a cover glass opposed to the diode, through which the energy is transmitted. The TO can is hermetically sealed. The hermetic sealing of the TO can is a time-consumsing and expensive process which adds to the overall expense of the LED or laser package. As well, the commonly known TO cans do not have the emission area of the diode aligned within the TO can in a consistently centered orientation. Thus, placement of the TO can in a uniform position does not provide for alignment of the diode to an optical connector and maximum power transmission is not achieved. Thus, alignment of the TO package becomes a time-consuming and expensive process.
Commonly known housings for optical transceivers require complex mechanical means in order to align the diode package, the lens, the bore and the optical waveguide ferrule. Mechanical means, such as a screw is commonly used to actively align the TO can within the housing.
Further, a molded plastic housing is often used having precision molded cavities specifically sized for receiving a diode package, another cavity specifically sized for receiving a lens and another cavity specifically sized for receiving an optical waveguide ferrule. Such an optical transceiver housing is often rendered ineffective in production due to variations in the alignment of the LED or laser relative to the TO can.
Often, optics housings are metallic so as to provide ruggedness, ease of machining complicated shapes, and to enhance shielding of electromagnetic fields. Ferrules connect to the optical package by way of inserting the ferrule into the optics housing. Attached to the ferrule is the fiber optic cable. The fiber optical cable conveys the optical signal. The optical package can either receive or create the optical signal and as such either transforms the received optical signal into an electrical signal or transforms an electrical signal into an optical signal. Presently, the majority of ferrules which are inserted into the optics housings are made of a ceramic material. To properly transmit the optical signal, the ferrule must be accurately positioned within the optics housing. The close fit between the metallic housing and the ceramic ferrule has resulted in a failure mode known as galling. Galling results in large amounts of material transfer between one or both of the contacting surfaces. At a certain point, the galling phenomenon is so insidious that it prevents the ferrule from being further inserted into the housing or from being removed from the housing of the optics housing. In order to prevent the galling phenomenon it has been known to provide a sleeve or insert in the housing so as to receive the ferrule, where the sleeve is made of a material similar to the material of the ferrule. Machining a ceramic material to exacting dimensional requirements is difficult and hence is expensive. The scrap rate is high and the time required to process such ceramic sleeves is high. The sleeves are machined to exacting dimensions since the ferrule must be received within the sleeve with very little clearance between the two so as to accurately position the ferrule within the optics housing. Since both the ceramic ferrule and the ceramic sleeve are not very compliant, the dimensions of the sleeve and the ferrule must be very accurate.
In view of the above, it is an object of the present invention to provide an optical device package which is quickly and inexpensively manufactured.
It is a further object of the present invention to provide an optical device package which may be easily aligned with an optical transceiver housing.
It is another object of the present invention to provide an optical package having a single optical axis.
It is another object of the present invention to provide an optical package housing formed using insert molding techniques in order to provide a quickly and inexpensively manufactured precision housing assembly.
It is still yet another object of the invention to provide an optical device package having a sleeve which prevents galling and is inexpensively manufactured.